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The X10 is the latest offering in the Maelstrom line from 4Sevens. Featuring a 26650 Li-ion battery, it looks a lot like the S12 - only now with a Cree XM-L emitter (X10) instead of the Luminus SST-90 (S12).

Packaging is fairly typical for the Maelstrom line. Included inside is the light, good quality belt pouch/holster, manual, and spare o-rings. There is no wrist lanyard (no attachment point on the light). Note that there is also no battery included – you must purchase a 26550 Li-ion rechargeable and charger separately. Conveniently, 4Sevens just happens to sell these …

Here’s what the required battery looks like:

My review sample came with a blue-wrapped 26650 (the original S12 used a green-wrapped 26550). I’ve asked 4Sevens, and have been informed that the two batteries are different, with the X10 blue-wrapped battery reformulated for the lower load with the XM-L. The S12 batteries will work in the X10, but not the reverse.

The light is wider than typical, due to the 26650 cell (i.e. 26650 refers to the battery width in mm, 26650 refers to the length in mm, 26650 refers to a cylindrical cell). But overall length is well within the standard range for lights that use this typical 65mm cell length.

Compared to the 2x18650 class of lights, the X10 seems downright tiny. The reason for this size comparison will become obvious once you see the output …

The X10 is a solid light. Black anodizing (manufacturer claims type III = HA) is slightly glossy on the smooth areas, like the rest of the Maelstrom line. Knurling is not overly aggressive, although there is more of it than typical on these sorts of lights, and I found the grip to be good. Lettering is bright - clear and sharp.

There are a generous number of square-cut machinist threads (anodized for tailcap lockout).

Note the switch is not an actual clicky. Pressing the plastic button simply pushes forward the circuit board slightly. This allows contact for momentary-on when the tailcap isn’t fully tightened. When fully tightened, the tailcap is locked-on and the button has no effect. Scroll down to my interface section for a discussion.

The X10 uses the Cree XM-L emitter, well centered on my sample, with a smooth reflector (although there are some fine concentric rings in it). I don’t have a S12 to compare, but it looks like they are using the same build for the X10, with a flat area of the reflector right around the smaller emitter in this case.

And now the white-wall beamshots. All lights are on their respective single cell rechargeable Li-ion battery source, about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences.

Output is quite high for a single-cell light – 4Sevens is clearly driving the XM-L at a relatively high level. The X10 has a very wide spillbeam, wider than most lights. This is likely due to the fairly wide and shallow reflector. However, the beam also has some artifacts in it up close, especially around the hotspot. There is also a very pronounced tint shift in the large and sharply defined secondary corona on my sample.

The X10 seems to have exact same interface as the S12 which preceded it.

Both lights use a pressure-style switch. When the tailcap is fully tightened, the light comes on and stays on. With the tailcap loosened a quarter-turn or so, you can press the switch button to activate the light in momentary mode (i.e. release the pressure switch, and it shuts off).

Mode switching between the two output modes is controlled by rapidly turning the light off and back on again within 1 sec. You can do this with either the momentary pressure switch or by twisting. If you wait longer than 1 sec before reactivating, the X10 memorizes the last mode you were in (i.e. comes back on in the last mode used next time you re-activate).

Although this is fairly straight forward, it can be annoying if you are someone who rapidly flashes your light off and back on (i.e. triggers mode switching if you do it under 1 sec). This means that momentary signaling is not possible with the light.

No PWM/Strobe

The X10 has just two constant output modes – no flashy, no blinky.

Testing Method:

All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan.

Effective November 2010, I have revised my summary tables to match with the current ANSI FL-1 standard for flashlight testing. Please see http://www.sliderule.ca/FL1.htm for a description of the terms used in these tables.

Let's start with a comparison to the 1x18650 lights:

Ok, the X10 is certainly in another league of output. Here is how it compares to the 2x18650 group of lights:

Max output on the X10 puts it squarely in the top-of-the-line class of XM-L lights. Throw is reasonable for the output, similar to the Fenix TK35 or JetBeam BC40.

Output/Runtime Comparison:

Note: My relative output scale is not linear for output across this range. Please see my Summary Tables above for lumen estimates.

Again, I'll start with the 1x18650 comparisons:

Runtime was bang on with the 4Sevens 1.8 hour estimate on Hi (i.e. 1hr 48 mins). On Lo, runtime was considerably less than the spec (i.e. 9 hours instead of 15). However, my lumen estimate was double that reported for the light (i.e. 200 lumens instead of 100 lumens).

A comment about the output level estimates – the X10 uses a partial regulation/step-down pattern over the run (likely a response to thermal management). Basically, the light seems to run mainly direct-drive, but with thermal regulation to step-down the light if it gets too hot. Under a cooling fan, using my crude conversion method (link above), I estimate the lumens to be ~770 at 3 mins into the run (i.e. ANSI FL-1 standard), but by 4.5 mins, it drops down to ~700 lumens. From 10-40 mins, it switches back and forth between ~670 and ~640 estimated lumens, before falling into a direct-drive pattern without thermal step-down for the rest of the run (until the protection circuit is tripped).

4Sevens thus seems to be conservatively using the lowest “regulated” level for lumen estimate for this light, even though it spends most of the time above this level. But again, I don’t have a calibrated integrating sphere to say for sure – this is a relative comparison based on lumen estimates of other lights.

Let's see how it compares to the 2x18650 class:

Output and runtime is pretty comparable to the 2x18650 lights (note I use only 2200mAh 18650s in my runtime testing above).

Beam has noticeable artifacts and tint shifting on my sample, but these are really only issues at close-range.

The light is not tightly regulated over its run, but seems to use some sort of thermal management to lower the output as necessary (which is actually a good thing, IMO). Note that all my runtimes are done under a cooling fan, which likely provides greater cooling than just hand-holding.

No primary battery option – 26650 Li-ion rechargeable only. Although in a pinch, you could use an 18650 IMR cell with something wrapped around it to create the appropriate thickness.

No wrist lanyard attachment point, the light cannot tailstand.

Preliminary Observations

The X10 is a solid light. It does what it does simply, with no fuss and no muss – blindingly bright Hi output, and a battery-sparing lower output.

Let's start with the output – the X10 is the brightest XM-L light I’ve seen running off a single cell. The X10 is brighter than my Thrunite Scorpion V2, which was my recent high-output champ on 1x18650. It's true the 26550 cell used here has higher capacity (and so can handle a drive current and discharge rate), but it's impressive that 4Sevens could drive the XM-L so high on 1x3.7V Li-ion source.

In fact, the X10 is solidly in the output class of my 2x18650 XM-L-based lights. The X10 matches the output, throw and runtime characteristics of this high output class.

The pressure switch is interesting, I haven’t seen one of these in awhile. Since there is no clicky, there are certainly no worries about handling the sort of current required here (i.e. the switch is just a press switch). The main gripe I have is the mode switching interface – whether you press on (momentary) or screw on (locked-on), flashing the tailcap switches modes. I would have preferred something like the old Surefire tactical two-stage pressure switch (i.e. Low comes on first, then Hi, as you press or screw tighter). But I guess Surefire has a patent on this, so it may not have been an option for 4Sevens.

In terms of the beam, you get a good balance here overall – a wider than typical spillbeam (good for near area examination), and a well-focused hotspot for maximum throw. But my sample is not the prettiest - there are some noticeable artifacts and tint shifting within the beam close-up. Still, these aren’t a problem at a distance (which is likely how you would use a high output light like this).

I don’t have other 26650-based lights to compare, but runtime seems very good for the output level and rated capacity of the cell. Again, the manufacturer specs seem conservative on Hi – 640 lumens was the lowest estimated output I saw over the thermally-managed first 40 mins or so (e.g. ANSI FL-1 estimate was ~770 in my case, but all my runtimes are done under a cooling fan). Runtime was bang on at 1.8 hours. On Low, I only got about 9 hours (instead of the rated 15), but my output estimate is twice that of the reported spec (i.e. 200 estimated lumens in my testing, compared to 100 lumen spec).

In terms of performance, the X10 is an impressive single-cell rechargeable light in the high-output XM-L class. It is certainly another compact option to consider in this class – especially if you are looking for as much power as possible in a small size.

I imagine they would if they could, given apparent user demand. I suspect this is difficult on the S12 (given the current that would be flowing through the clicky switch), but it might be easier on the X10. Of course, this would also lengthen the light somewhat.

Personally, I'd vote for something like the classic Surefire Hi/Lo tactical pressure switch instead, as this would also resolve the issue of momentary signaling.

Excellent review as usual. I'm looking forward to the outdoor Beam shots!
Compared to the scorpion does it throw farther or about the same?
I Just got the Scorpion V2 with turbo head a week ago and love it! Bought it based on your review!! No regrets..

Excellent review as usual. I'm looking forward to the outdoor Beam shots!
Compared to the scorpion does it throw farther or about the same?
I Just got the Scorpion V2 with turbo head a week ago and love it! Bought it based on your review!! No regrets..

They are similar overall. The X10 has a brighter and more sharply defined hotspot, and so throws farther than the Scorpion V2 (but the difference isn't huge). The Scorpion has a brighter corona, which may help light up things at moderate distances outside the main beam. The X10 has a wider spillbeam, noticeable only at close-range.

Originally Posted by jhc37013

During the first 45mins it looks like the thermal regulation cuts in and out several times, it seems sudden and often during this part of the runtime, do you find that annoying especially with the tint shift?

Not really. Even with the biggest "dip" around 4.5mins in, we are only talking about a ~10% drop in output. The other smaller "dips and jumps" are more like ~5% each. That's enough to notice a subtle change, but it's not really enough to be a major distraction.

Of course, all of that is under a cooling fan. The drops in thermal management might be a bit higher with only hand-holding.

Could the artifacts in the beam be because of the part that keeps the emitter aligned? I can barely make them out but the dark spots almost look like the same pattern as the emitter "seat".

Interesting theory. Looking more closely, I can see the the base of the reflector is not perfectly flat (i.e. it has some curvature to it). But the curvature is consistent, I don't see any evidence of the "seat" poking through. More likely, I suspect the curved base of the reflector is picking up reflection from around the emitter die/dome (i.e. maybe from the four corners outside the die?).

Originally Posted by HIDblue

Great review selfbuilt. You're right...those are some noticeable artifacts around the beam up close, but I wonder if you'd notice it outside of white wall hunting?

Always a good question - you certainly wouldn't notice it outside at anything with a non-uniform texture. But you may see it when shining on the side of a house or a garage door. Personally, I'm not bothered by it outdoors, but you will see inside a house.

And not for nothing, but what the heck happened to your finger?

I was waiting for someone to ask that. Whacked it with a hammer two months ago, shattered the top half of the distal phalanx. I was hammering in a deck fencing board, when I hit a pile of concrete under the surface, and my left hand slipped (talk about being caught between a rock and a hard place). You can see the progression of the brusing under the nail, starting from my Thrunite Scropion V2, which was just a week or so after the incident (I took the buddy-taping off for that light). The nail is starting to come off now, so I imagine the next sets of lights won't look too pretty.

Here's what it looked like underneath:

I have pretty much full function back now, just some loss of senstitvity in the tip (plus it's a little wider than it used to be ... ).

Excellent reply's I was waiting for some of those answers before I place my order this weekend. Selfbuilt what do you make of the different battery's for the S12 and X10, the X10 battery supposedly can't handle the high current of the S12 so this has me wondering if the S12 battery may be better quality. I mean they are the same price so what should one do, have you did any test with the S12 battery in the X10?

Regarding the corona - we've experimented with so many prototype reflectors and eventually we settled for the best compromise. The warmer tint actually comes from sharper angle of incidence - if you think about it the light coming at 180 degrees actually travels through more phosphor thus causing a warmer light. Light coming perpendicular from the die will be the coolest. Pretty much every single LED we've worked with in our labs has this characteristic. Maybe one day they'll be able to make dies that are convex and not flat - they the problem of delta tint would be solved.

Until then we have to make engineering compromises to make up for the current flat-square LED paradigm. There are two distinct ways to ease this delta tint in the corona. 1) add stippling/orange peel at the cost of throw 2) use a different foci for the reflector area around the LED which has the highest incident angle.

Since our target was to make the shortest (stubby) thrower we opted not to do the orange peel as that takes away from the spot intensity and angle. We changed the foci of the reflector area just around the LED, thus spreading out that part of the reflection.

I had some test reflectors that do now have this foci adjustment and trust me the corona is more pronounced in shape as well as tint. So the product reflector eases the tint shift while maintaining throw.

Sorry I got a little technical here and probably said too much (competition is always watching and reading notes) but I felt to disclose this to my cpf family

Selfbuilt what do you make of the different battery's for the S12 and X10, the X10 battery supposedly can't handle the high current of the S12 so this has me wondering if the S12 battery may be better quality. I mean they are the same price so what should one do, have you did any test with the S12 battery in the X10?

4Sevens would be in the best position to answer that (I do not have an S12 battery to compare). I just noticed the different wrapper, and so inquired. Don't have any more specifics.

Originally Posted by 4sevens

if you think about it the light coming at 180 degrees actually travels through more phosphor thus causing a warmer light. ... There are two distinct ways to ease this delta tint in the corona. 1) add stippling/orange peel at the cost of throw 2) use a different foci for the reflector area around the LED which has the highest incident angle. ... Since our target was to make the shortest (stubby) thrower we opted not to do the orange peel as that takes away from the spot intensity and angle.

Thanks for joining in David.

Your explanation makes sense. I have seen some tint shifting before in coronas, though not usually this pronounced. But of course, the far more common solution that most makers have opted for has been texturing the reflector (one imagines a cheaper option as well ).

Originally Posted by MichaelW

For a second there, I thought that image of the bones was from the flashlight
It is called 'X'10...

Just as well it isn't ... I'd have quite the gamma dose by now if LEDs emitted high-energy.

I'm glad throw was kept as a priority with this particular light (no OP reflector.) I think it's safe to say that there is currently no shorter length light (asphericals aside obviously) that will out throw the X10. That, and astounding runtime for this output level in a single cell light make the X10 unique.

Excellent reply's I was waiting for some of those answers before I place my order this weekend. Selfbuilt what do you make of the different battery's for the S12 and X10, the X10 battery supposedly can't handle the high current of the S12 so this has me wondering if the S12 battery may be better quality. I mean they are the same price so what should one do, have you did any test with the S12 battery in the X10?

I'm guessing the difference is the protection circuit, but not the quality. The X10's battery would not allow higher current draws specific to the S12, but sufficient for the X10. Safer perhaps.

Great review as always. Your finger looks worse now than in the prior reviews - ouch.

Thanks David for the technical explanation - very interesting stuff.

What a great light. I don't have any 26650 cells but I guess I'm going to have to add some because this light is worth having. What a great little light. I am amazed that the X10 keeps up the the TK35 in output, throws farther, has longer runtime, AND it is WAY smaller. amazing. I can't wait to have one in my hands.

I was reading over at the Marketplace and David says the flux and bin codes will vary, some could be T6 and others U2. This had me thinking maybe this test sample has the U2 and that is why it reaches higher output levels and maybe the T6 is closer to the 640lmns, just a thought.

I'm impressed how efficient the driver is - you get roughly the same lumenhours out of 1x3900mAh as the 2x2200mAh lights, without the hassle of cell PCB protection jumping in (always at too low voltage IMO), and finding a pair of balanced cells.

If the light would have something like the tighen->high / loosen->low interface (doesn't matter if head or tail) + momentary clicky, I would be all over it - I don't need so many flashlights, so if I buy another one, the "entertainment value" must be high.

@David: Thanks for the explanation! I love the more technical comments, they are the most enlightening and the main reason I spend my time here!

I was reading over at the Marketplace and David says the flux and bin codes will vary, some could be T6 and others U2. This had me thinking maybe this test sample has the U2 and that is why it reaches higher output levels and maybe the T6 is closer to the 640lmns, just a thought.

I was reading over at the Marketplace and David says the flux and bin codes will vary, some could be T6 and others U2. This had me thinking maybe this test sample has the U2 and that is why it reaches higher output levels and maybe the T6 is closer to the 640lmns, just a thought.

Originally Posted by 4sevens

All review units were T6.

I suspect it has more to do with cooling - all my runtimes are done under a cooling fan.

ti-force has done a nice analysis of various cooling options on the S12 and X10 in his review, and you can see it drops lower with less cooling. Although he didn't test a cooling fan specifically, I know from my own experimentation that a fan provides better cooling that a full-contact hand grip for hand cooling. So I suspect I would have had lower numbers if I hadn't used a fan (based on ti-force's results). And of course, my lumen estimates are computed, not direct measures in a calibrated sphere, so the degree of uncertainty in the measures is high.

I suspect it has more to do with cooling - all my runtimes are done under a cooling fan.

OK yes that makes since and thanks for another excellent review I just placed my order through 4sevens.

This great little thrower with moderate spill is going to fill a void I have, like you said it does as well as most 2x18650 XM-L light's and I can't go EDC'ing those around on my belt EDC. I think it will complement the SC600 I carry in my pocket well.

I have 2 questions. I know they are not quite in the same category but how does the X10 compare to olight sr51 in therms of throw and output and overall usability. The description says the X10's battery should only be charged with 4sevens charger. Would it be safe to charge the 26650 in ultrafire WF 139 charger ? I saw somewhere that it can accomodate a single 26650 even thou' it wasn't designed for it initially.

Does the X10 roll around a lot? Say you were to lay it down on a slight slope, does any of the machining prevent it from rolling?

Yes, it rolls somewhat, as you would expect. But the cut-outs at the base of the head help stabilize it (as long you don't give it a lot of force to set it rolling).

Originally Posted by MTL-TL

I have 2 questions. I know they are not quite in the same category but how does the X10 compare to olight sr51 in therms of throw and output and overall usability. The description says the X10's battery should only be charged with 4sevens charger. Would it be safe to charge the 26650 in ultrafire WF 139 charger ? I saw somewhere that it can accomodate a single 26650 even thou' it wasn't designed for it initially.

Don't have the SR51 yet to compare, but that is of course a larger light (with higher output). Should be reviewing it later this summer, and will include the X10 in the comparison.

As for a charger, I would personally only use one rated for use with 26650 (without modification).

I wish Thrunite and 4Sevens would take some of the focus off of "Tactical" lights. I'd love to have one as a work light. For this it needs to be able to be set both on it's side without rolling and tailstand. Seems like the focus is all on tactical.